1. Field of Invention
The present invention relates to alertness monitoring systems and to methods of monitoring alertness, and, in particular, to systems and methods for monitoring the alertness of drivers, such as drivers of vehicles, including motor vehicles, trains, airplanes, boats and the like, and to systems and methods for monitoring the alertness of security personnel.
2. Description of the Related Art
The injuries and deaths resulting from crashes involving fatigued and sleepy drivers have led to increasing concern. For this reason, various motor vehicle alertness monitoring systems have is been provided that, among other things, monitor the onset of drowsiness of the driver.
Existing sensor technologies for monitoring the drivers of motor vehicles, and especially for monitoring the onset of drowsiness, include systems designed to measure eye closure. One such system is called the PERCLOS system developed by the University of Virginia. PERCLOS is defined as the portion of time within a one minute time interval during which the eyes are occluded at least 80%. The PERCLOS system (as further developed by Carnegie-Mellon University) uses two different wavelengths of infrared (IR) radiation (850 nm and 950 nm) to illuminate a driver""s face and an IR camera to view the driver""s face and make measurements of the auto-reflection of the eye. The eye is fairly transparent to the 850 nm radiation until the retinal surface at the back of the eye. At the retina, the radiation is reflected, causing a phenomenon known as the xe2x80x9cglowing pupilxe2x80x9d effect. The 950 nm radiation, on the other hand, is mostly absorbed by the water molecules in the eye, therefore producing almost no reflection. The image obtained from the 950 nm radiation is subtracted from the image obtained with the 850 nm radiation, resulting in an image that contains only the retinal reflections. The PERCLOS device utilizes the above approach to detect and measure eye blink by measuring how the eyelids obscure this auto-reflection.
The above system has at least three disadvantages. First, use of the PERCLOS system in sunlight presents significant problems, since the incident sunlight IR can overwhelm detection from the measurement of the auto-reflection of the IR energy. Second, the IR energy cannot effectively pass through sunglasses, thus making use of the PERCLOS system on a driver wearing sunglasses practically superfluous. Third, the system does not function effectively with individuals having dark skin pigment, since the pigment is also found in the eye, which significantly reduces the reflected intensity of the 850 nm IR radiation. Although various methods of overcoming these disadvantages have been proposed, none of them have shown the desirable level of effectiveness. One such method has been proposed to increase the incident IR energy on the eye. However safety limitations on eye exposure to IR energy prevent such a measure. Another such method is the provision of video systems that would eliminate the need for IR imaging altogether. Yet another such method, which aims at overcoming the effect of sunlight, is to use a pulsed IR radiation source and to detect the pulsed reflection with a pulsed synchronized detector. However, these systems are still in the early stages of development and have not yet provided appreciable results
In addition, it has not been uncommon for security personnel, such as those sitting in front of TV security monitors, especially for mission critical monitoring such as at nuclear sites, to lose their alertness, such as by becoming drowsy and falling asleep. In this way, the security and safety of those sites has been compromised.
The present invention overcomes the drawbacks of alertness monitoring systems of the prior art while advantageously allowing alertness monitoring, and, in particular, the monitoring of the alertness of drivers, such as drivers of vehicles, including motor vehicles, trains, airplanes, boats and the like, or the monitoring of security personnel, for the purpose of detecting the onset of drowsiness.
The present invention provides an alertness monitoring system for monitoring the alertness of a subject; The system comprises a Doppler sensor adapted to sense a parameter pertaining to the subject, the sensor being one of an acoustic sensor and a microwave sensor; and control electronics adapted to be coupled to the sensor for processing signals therefrom. The control electronics include a processing device having an alertness monitoring algorithm embedded therein adapted to process the signals from the sensor thereby generating processed signals and to determine whether an impairment of alertness event pertaining to the subject has occurred. The control electronics further include a stimulus control coupled to the processing device and being controlled by the alertness monitoring algorithm for providing feedback to the subject based on a determination of whether an impairment of alertness event pertaining to the subject has occurred.
The present invention further provides a method for monitoring the alertness of a subject comprising the steps of: disposing a Doppler sensor to sense a parameter pertaining to the subject, the sensor being one of an acoustic sensor and a microwave sensor; processing signals from the sensor through an alertness monitoring algorithm for generating processed signals; determining whether an impairment of alertness event pertaining to the subject has occurred based on the processed signals; and providing feedback to the subject based on a determination of whether an impairment of alertness event pertaining to the subject has occurred.
In addition, the present invention pertains to an alertness monitoring system comprising: a Doppler sensing means disposed to sense a parameter pertaining to the subject, the sensing means being one of an acoustic sensor and a microwave sensor; means adapted to be coupled to the sensing means for processing signals therefrom thereby generating processed signals and for determining whether an impairment of alertness event pertaining to the subject has occurred; and means coupled to the means for processing for providing feedback to the subject regarding a determination of whether an impairment of alertness event pertaining to the subject has occurred.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are only intended to provide a further explanation of the present invention, as claimed. The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate several exemplary embodiments of the present invention and together with description, serve to explain the principles of the present invention.